Experimental assessment of textured tools with nano-lubricants in orthogonal cutting of titanium alloy

In this study, we investigated the effects of composite nano-Cu/WS₂ lubricating oil and single-point diamond indentation-textures on improving the cutting performance of YG8 cemented carbide tools, which is crucial for textures tool applications. The aims of the study were to improve wear resistance and reduce chip adhesion at the tool’s rake face in cutting of titanium alloys. Dot textures with different spacings were fabricated on the surface of YG8 cemented carbide tools through the single-point diamond indentation method, and composite nano-Cu/WS₂ lubricating oil was prepared. Orthogonal cutting tests were carried out under dry cutting and minimal quantity lubricated (MQL) conditions. Investigate the effect of different texture spacing on the cutting performance in the light of cutting forces, friction coefficient, the deformed chip thickness, tool adhesions, and chip morphology. The results show that the dot texture effectively improved the lubrication conditions in machining titanium alloys under the MQL conditions. The dot texture is effective at low speed in the dry cutting conditions. With the increase of cutting speed, the friction coefficient of dot texture tool is affected by texture spacing, and the friction coefficient of DT-200 tool is the smallest. In addition, composite nano Cu/WS₂ lubricating oil forms a lubricating film on the wear path by atomizing the lubricating oil and stores it in the dot texture, which enhances the anti-wear performance in the cutting process and reduces the cutting force and friction coefficient at the tool chip interface. By evaluating cutting force, friction coefficient, chip and tool morphology, it is concluded that DT-100 tool is more effective in improving lubrication conditions.

     

Analysis of machinable structures and their wettability of rotary ultrasonic texturing method

Tailored surface textures at the micro- or nanoscale dimensions are widely used to get required functional performances. Rotary ultrasonic texturing (RUT) technique has been proved to be capable of fabricating periodic micro- and nanostructures. In the present study, diamond tools with geometrically defined cutting edges were designed for fabricating different types of tailored surface textures using the RUT method. Surface generation mechanisms and machinable structures of the RUT process are analyzed and simulated with a 3D-CAD program. Textured surfaces generated by using a triangular pyramid cutting tip are constructed. Different textural patterns from several micrometers to several tens of micrometers with few burrs were successfully fabricated, which proved that tools with a proper two-rake-face design are capable of removing cutting chips efficiently along a sinusoidal cutting locus in the RUT process. Technical applications of the textured surfaces are also discussed. Wetting properties of textured aluminum surfaces were evaluated by combining the test of surface roughness features. The results show that the real surface area of the textured aluminum surfaces almost doubled by comparing with that of a flat surface, and anisotropic wetting properties were obtained due to the obvious directional textural features.     

Performance of cutting tools with dimple textured surfaces: A comparative study of different texture patterns

Recently, surface texturing has received much attention as a method of enhancing the tribological properties of a cutting tool surface. However, effective texture patterns and dimensions on a tool surface are still difficult to obtain and suitable textures can be obtained only by trial and error. In order to overcome this problem, we newly develop cutting tools with dimple-shaped textures having different dimensions and arrays, generated on the tool rake face. In addition, we evaluate their crater wear resistance and cutting forces in steel material cutting. Furthermore, under various cutting conditions, the performances of the cutting tools with dimple-shaped textures are compared with those of tools with groove-shaped textures in order to establish a guideline for designing appropriate surface textures on cutting tool surfaces. A series of cutting experiments demonstrate that the dimple textures significantly improve the crater wear resistance and the tribological behavior on the tool rake face, and they exhibit a superior performance compared with those with groove textures, especially in a severely lubricated environment.     

MACHINABILITY OF AI/SiC PARTICULATE METAL-MATRIX COMPOSITES UNDER DRY CONDITIONS WITH CVD DIAMOND-COATED CARBIDE TOOLS

This article investigates the machinability of two Al/SiC particulate metal-matrix composites (MMC) with 5 and 15% vol. SiC particles. Dry turning tests were performed with three different CVD diamond-coated tools. In a first series of experiments, various cutting conditions were tested and their effects on tool wear mechanisms were studied. For the second series, optimal cutting conditions were chosen and tool life was investigated. The consumed spindle power was continuously measured; it was shown that its increasing follows the evolution of the tool wear criteria. Residual stresses at the machined surfaces were measured by X-ray diffraction technique. The effect of SiC percentage in the MMC on the machinability was also investigated.     

Investigation of the performance of carbide cutting tools with hard coatings in hard milling based on the response surface methodology

Machining of hard materials has become a great challenge for several decades. One of the problems in this machining process is early tool wear, and this affects the machinability of hard materials. In order to increase machinability, cutting tools are widely coated with nanostructured physical vapor deposition hard coatings. The main characteristics of such advanced hard coatings are high microhardness and toughness as well as good adhesion to the substrate. In this paper, the influence of hard coatings (nanolayer AlTiN/TiN, multilayer nanocomposite TiAlSiN/TiSiN/TiAlN, and commercially available TiN/TiAlN) and cutting parameters (cutting speed, feed rate, and depth of cut) on cutting forces and surface roughness were investigated during face milling of AISI O2 cold work tool steel (～61 HRC). The experiments were conducted based on 3¹³ factorial design by response surface methodology, and response surface equations of cutting forces and surface roughness were obtained. In addition, the cutting forces obtained with the coated and uncoated tools were compared. The results showed that the interaction of coating type and depth of cut affects surface roughness. The hard coating type has no significant effect on cutting forces, while the cutting force F _z is approximately two times higher in the case of uncoated tool.     

Digraph and matrix method to evaluate the machinability of tungsten carbide composite with wire EDM

Machinability aspect is of considerable importance for efficient process planning in manufacturing. Machinability of an engineering material may be evaluated in terms of the process output variables like material removal rate, processed surface finish, cutting forces, tool life, specific power consumption, etc. In this paper, graph theoretic approach (GTA) is proposed to evaluate the machinability of tungsten carbide composite. Material removal rate is considered as a machinability attribute of tungsten carbide to evaluate the effect of several factors and their subfactors. Factors affecting the machinability and their interactions are analyzed by developing a mathematical model using digraph and matrix method. Permanent function or machinability index is obtained from the matrix model developed from the digraphs. This index value helps in quantifying the influence of considered factors on machinability. In the present illustration, factors affecting machinability of tungsten carbide are grouped into five broad factors namely work material, machine tool, tool electrode, cutting conditions, and geometry to be machined. GTA methodology reveals that the machine tool has highest index value. Therefore, it is the most influencing factor affecting machinability.     

纳米材料在切削铸铁刀具中的应用

简要介绍了纳米复合材料的特点。阐述了铸铁材料尤其是白口铸铁的切削性能。从铸铁材料和切削铸铁的刀具材料两个方面,综述了提高铸铁切削性能的研究状况。详述了纳米陶瓷基复合刀具材料的制备方法及刀具对铸铁切削性能的研究进展。对纳米材料在切削铸铁的刀具材料中应用的前景提出了建议。     

A method for identification of geometrical tool changes during machining of titanium alloy Ti6Al4V

There exists an increasing demand for cost and time-efficient cutting tests for describing the performance of different combinations of cutting tools and workpiece materials in the cutting process both in industry and academia. Cutting tools are expected to withstand the heat and the pressure developed during the machining of difficult-to-machine materials such as Ti6Al4V. This article introduces a new test method which may be used in order to analyze both the machinability of a workpiece material as well as the cutting tool behavior. The experiments were performed by using a predefined sequence of feeds, a so-called Stepwise Increased Feed Test. A gradually increased load on the cutting edge was thus applied up to the point where plastic deformation of the cutting edge was obtained. The limit for the initial change in tool geometry was identified through analysis of measured cutting forces.     

Tool life and wear mechanism of coated and uncoated Al2O3/TiCN mixed ceramic tools in turning hardened alloy steel

The focus of this paper is the continuous turning of hardened AISI 52100 (～63HRc) using coated and uncoated ceramic Al₂O₃–TiCN mixed inserts, which are cheaper than cubic boron nitride (CBN) or polycrystalline cubic boron nitride (PCBN). The machinability of hardened steel was evaluated by measurements of tool wear, tool life, and surface finish of the workpiece. Wear mechanisms and patterns of ceramic inserts in hard turning of hardened AISI 52100 are discussed. According to the results obtained, fracture and chipping type damages occur more frequently in uncoated tools, whereas crater wear is the more common type of damage in TiN coated tools. Most important result obtained from the study is that TiN coating and crater wear affect chip flow direction. In uncoated ceramic tool, the crater formation results in decrease of chip up-curl radius. Besides, uncoated cutting tool results in an increase in the temperature at the tool chip interface. This causes a thermal bi-metallic effect between the upper and lower sides of the chip that forces the chip to curl a smaller radius. Chips accumulate in front of the tool and stick to the workpiece depending on the length of the cutting time. This causes the surface quality to deteriorate. TiN coating not only ensures that the cutting tool is tougher, but also ensures that the surface quality is maintained during cutting processes.     

微织构Al_2O_3-TiC陶瓷刀具切削性能仿真研究

前刀面有微织构的刀具与无织构刀具的切削性能不同。为了研究Al_2O_3-Ti C陶瓷刀具前刀面凹坑微织构分布对刀具切削性能的影响,使用ABAQUS对陶瓷刀具进行三维建模,将模型导入有限元分析软件Advantedge中,在相同条件下,对无微织构和有微织构刀具进行三维切削仿真,对比其切削力、切削温度及应力分布,结果表明,具有特定凹坑微织构参数的Al_2O_3-Ti C刀具在切削过程中可降低切削力,改善温度和应力分布。     

粉末冶金零件的车削加工

分析了粉末冶金零件的机械性能和加工难点，从机械加工的角度探讨了有利于提高粉末冶金加工性能的刀具材料和切削参数，并推荐使用整体PCBN刀具，同时也介绍了金属陶瓷和硬质合金刀具的应用场合。     

Turning titanium metal matrix composites (Ti-MMCs) with carbide and CBN inserts

Despite excellent mechanical and physical features of titanium metal matrix composite (Ti-MMC), hard and abrasive ceramic particles within the matrix structure, as well as high price, may lead to severe difficulties on machining and machinability of Ti-MMCs. Review of literature denotes that only limited studies are available on machining Ti-MMCs with commercial cutting tools under various cutting conditions and cutting tools/inserts. Furthermore, limited studies are available on machinability attributes of Ti-MMC under various cutting conditions used. Therefore, to remedy the lack of knowledge observed, this work intends to report turning Ti-MMCs with carbide, and cubic boron nitride (CBN) inserts under various cutting conditions. The mean values of surface roughness (R_a) and directional cutting forces, as well as flank wear (V_B) were studied as the machinability attributes. The microstructural evaluations were conducted to discover the wear modes. Furthermore, the statistical tools were used to present the factors governing machining attributes studied. Adhesion, abrasion, and oxidation were observed as the principle wear modes on the flank sides of the tested inserts. According to experimental results and statistical analysis, the R_a and V_B could be controlled by cutting parameters only when CBN inserts were used. Despite the inset used, factors governing both responses were not identical. Although average cutting forces were directly affected by cutting parameters used, however, the relatively low correlation of determination (R²) of directional cutting forces can be attributed to effects of cutting speed, elevated temperature in the cutting zone as well as rapid tool wear which are all correlated to others.     

Low-temperature machining in a fully submerged cryogenic environment

The role of an immersive cryogenic environment in affecting material response in machining was explored using dynamometry, calorimetry, electron microscopy, and microindentation. Effects of tool rake angle on energy dissipation, stored energy of cold work, deformed microstructure, and hardening were evaluated for machining under a fully submerged cryogenic cutting environment and a dry cutting environment. Sustained immersion of the cutting zone in liquid nitrogen resulted in greater energy dissipation and hardening in the work and machined subsurface. This increased hardening at low temperature was directly linked to greater microstructure refinement and a lower fraction of dissipated energy stored in the form of added defects and grain boundaries. Various microstructure types with domain sizes from microscale to nanoscale were developed in the machined chips, depending on the rake angle and temperature used.     

Evaluation on Effectiveness of CVD and PVD Coated Tools during Dry Machining of Incoloy 825

With wide applications of nickel-based superalloys in strategic fields, it has become increasingly necessary to evaluate the performance of different advanced cutting tools for machining such alloys. With a view to recommend a suitable cutting tool, the present work investigated various machinability characteristics of Incoloy 825 using an uncoated tool, chemical vapor deposition (CVD) of a bilayer of TiCN/Al₂O₃, and physical vapor deposition (PVD) of alternate layers of TiAlN/TiN-coated tools under varying machining conditions. The influence of cutting speed (51, 84, and 124 m/min) as well as feed (0.08, 0.14, and 0.2 mm/rev) was comparatively evaluated on surface roughness, cutting temperature, cutting force, coefficient of friction, chip thickness, and tool wear using different cutting tools. Although the CVD-coated tool was not useful in decreasing surface roughness and temperature, a significant reduction in cutting force and tool wear could be achieved with the same coated tool under a high cutting speed of 124 m/min. On the other hand, the PVD-coated tool outperformed the other tools in terms of machinability characteristics. This might be attributed to the excellent antifriction and antisticking property of TiN and good toughness due to the multilayer configuration in combination with a thermally resistant TiAlN phase. Adhesion, abrasion, edge chipping, and nose wear were the prominent wear mechanisms of the uncoated tool, followed by the CVD-coated tool. However, remarkable resistance to such wear was evident with the PVD TiAlN/TiN multilayer-coated tool.     

Environmentally conscious hard turning of cemented carbide materials on the basis of micro-cutting in SEM: stressing four kinds of cemented carbides with PCD tools

Environmentally conscious hard turning and technology has placed more importance on the machining process. In this research, the possibility of environmentally conscious hard turning of cemented carbides was studied. The effects of cutting methods of dry and wet (vegetable oil mist, and mineral oil) and work material on cutting resistance and wear characteristics of cutting tools were experimentally investigated. The turning and micro-cutting process in SEM was carried out by using four kinds of tungsten carbides with the PCD cutting tools. Specifically, an emphasis was put on the effect of WC and Co additives in four kinds of cemented carbides on machinability and tool wear characteristics. The tool wear width and the cutting resistances were measured, and the worn flank was observed.     

Crater and flank wear resistance of cutting tools having micro textured surfaces

We have proposed cutting tools with various textured surfaces to increase cutting tool life. Our previous studies have developed cutting tools having periodical stripe-grooved surfaces on their rake face formed using femtosecond laser technology, which displayed high crater wear resistance in cutting of steel materials. In this study, the mechanism for suppressing the crater wear on the tool surface and the relationship between texture dimensions and wear resistance were investigated to provide a guideline for developing tools with textured surfaces. Furthermore, we newly introduced the textured surfaces into a flank face of cutting tools to improve flank wear resistance. Face milling experiments on steel materials exhibited that the newly developed tool having the textured flank face significantly reduced the flank wear. Moreover, the influences of texture dimensions and cutting conditions on the flank wear resistance were also discussed.     

Investigations of flank wear, cutting force, and surface roughness in the machining of Al-6061�CTiB2 in situ metal matrix composites produced by flux-assisted synthesis

This paper presents the results of an experimental investigation on the machinability of in situ Al-6061?CTiB₂ metal matrix composite (MMC) prepared by flux-assisted synthesis. These composites were characterized by scanning electron microscopy, X-ray diffraction, and micro-hardness analysis. The influence of reinforcement ratio of 0, 3, 6, and 9?wt.% of TiB₂ on machinability was examined. The effect of machinability parameters such as cutting speed, feed rate, and depth of cut on flank wear, cutting force and surface roughness were analyzed during turning operations. From the test results, we observe that higher TiB₂ reinforcement ratio produces higher tool wear, surface roughness and minimizes the cutting forces. When machining the in situ MMC with high speed causes rapid tool wear due to generation of high temperature in the machining interface. The rate of flank wear, cutting force, and surface roughness are high when machining with a higher depth of cut. An increase in feed rate increases the flank wear, cutting force and surface roughness.     

表面微凹坑和纹理方向对界面摩擦的耦合影响

选取三种不同纹理的铝合金试样,并在试样上加工不同面积占有率的规则圆形微凹坑,利用自制的摩擦试验装置,在油润滑条件下以不同接触压力进行摩擦试验,试验过程中滑动方向与表面纹理方向的夹角分别为0°、45°、90°。利用非接触式三维轮廓仪测量试验前后试样的三维表面形貌,并选取Sa、Str、Vvv、Vvc等表面表征参数来分析滑动接触界面表面形貌的变化。结果表明：表面纹理方向的差异导致铝合金表面在滑动接触摩擦过程中表现出各向异性,而在其表面加工不同面积占有率的微凹坑,减弱了铝合金表面纹理方向性对界面摩擦的影响,反映出表面微凹坑和纹理对界面摩擦的耦合作用。同时界面摩擦对试件的表面形貌也有明显的影响,Str、Vvv、Vvc在试验后发生了规律性的变化。     

Micro Textures in Concentrated-Conformal-Contact Lubrication: Effect of Distribution Patterns

Micro-scale textures may be engineered into surfaces for lubrication performance improvement. It is expected that a carefully chosen texture helps retain lubricant and enhances the hydrodynamic effect at the interface. The concept of model-based virtual texturing enables textured surfaces to be generated and “tested” through numerical simulations. This paper reports virtual texturing and simulation of a group of textured surfaces in a lubricated concentrated contact. The focus of the study is on the selection of texture distribution patterns based on their lubrication performance. Patterns of fishbone, sinusoidal, triangular, and honeycomb distributions have been investigated. The effects of texture direction, orientation angle, feature continuity, and aspect ratio are also studied. The results indicate that, for the given material and geometry system under the given conditions in the present work, the textures generating the strongest hydrodynamic lifting are short grooves with a small aspect ratio and sinusoidal waves of a small wavelength/amplitude ratio propagating in the motion direction.     

Performance comparison of conventional and wiper ceramic inserts in hard turning through artificial neural network modeling

Hard turning with ceramic tools provides an alternative to grinding operation in machining high precision and hardened components. But, the main concerns are the cost of expensive tool materials and the effect of the process on machinability. The poor selection of cutting conditions may lead to excessive tool wear and increased surface roughness of workpiece. Hence, there is a need to investigate the effects of process parameters on machinability characteristics in hard turning. In this work, the influence of cutting speed, feed rate, and machining time on machinability aspects such as specific cutting force, surface roughness, and tool wear in AISI D2 cold work tool steel hard turning with three different ceramic inserts, namely, CC650, CC650WG, and GC6050WH has been studied. A multilayer feed-forward artificial neural network (ANN), trained using error back-propagation training algorithm has been employed for predicting the machinability. The input?Coutput patterns required for ANN training and testing are obtained from the turning experiments planned through full factorial design. The simulation results demonstrate the effectiveness of ANN models to analyze the effects of cutting conditions as well as to study the performance of conventional and wiper ceramic inserts on machinability.